President Trump returned from his 12-day trip to Asia Tuesday night, with few major gaffes to answer for but few accomplishments to show for it, either—a fact he underscored with a strange “what I did on my fall vacation” speech Wednesday that failed to produce the “major” announcement he’d promised.

Trump headed out on his trip shortly after Special Counsel Robert Mueller’s first indictments and guilty plea, and the administration expressed some concern about that. “He worries about his ability to negotiate with various entities and how much he’s hamstrung by this,” a senior White House official told CNN, adding that Trump felt he’d be in a better position once the investigation was resolved.

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Unfortunately for Trump, that could be months or years down the line. How will that affect his ability to conduct foreign policy? The record of previous presidents facing probes like Mueller’s shows that in fact they have turned to global affairs as a forum where they can make a difference and get things done even as domestic politics becomes a gridlocked nightmare for them. But they’ve relied on having a competent and carefully compartmentalized staff, and even so, the presence of an investigation can reduce what an administration can achieve.

“You can get work done, and you can make progress,” says David Gergen, who worked in the Nixon White House during Watergate and then in the Clinton White House during the early days of the Whitewater probe. “Investigations can weaken the White House, but you have to convince everybody else to keep working. I think it’s extremely important that everybody keep their bearings, that they’re not panicked, they’re not lashing out.”

But that sort of message control, and staff control, has been beyond the abilities of the Trump team since the start, making it even more challenging for them to achieve now. Moreover, the task of keeping an even keel starts with a firm hand on the helm—and this White House has struggled to cope with a president whose announcements often take his own staff by surprise. Nixon’s temper was legendary; Clinton, Gergen recalls, was prone to volcanic but short-lived outbursts, but he too was largely predictable. By contrast, “the present White House doesn’t have any sense of what the current president is going to say or do next.”

Nixon and Clinton were not alone in facing special-prosecutor investigations—Ronald Reagan did as well, for Iran-Contra. But that case is perhaps less useful as an analogue. For one, it concerned the conduct of foreign affairs, circumscribing the president from global moves in a different way. For another, although Reagan achieved few major things after the start of the Iran-Contra affair, he was also deep in his second term, a point at which presidents often achieve little anyway.

Both Nixon and Clinton viewed foreign affairs as a place where they could make a difference—both in the world and in their political standing—even as they lost traction domestically. Congress and the political press were consumed with their scandals, but overseas, the executive branch could work largely on its own.

It helped that both Nixon and Clinton invested a great deal of effort in foreign affairs. Nixon was the most traveled president up to that time, setting the precedent for the frequent-flying commander in chief, and had built genuine relationships with many of his counterparts abroad. In August 1973, a New York Times survey of foreign leaders found that “although foreign leaders and public figures now seem to take the Watergate scandal more seriously than they did a few months ago, the affair has not so far cut deeply into their widespread support for Mr. Nixon’s course in foreign policy,” and that “there has been no sign that Watergate has crippled any ongoing negotiations or otherwise set back normal diplomatic business.”

“You have to convince everybody else to keep working. I think it’s extremely important that everybody keep their bearings, that they’re not panicked.”

Speaking to the Miller Center at the University of Virginia in 2005, Clinton’s national-security adviser, Sandy Berger, recalled a feeling of solidarity during the Monica Lewinsky scandal.

Since Clinton was under investigation for most of his presidency, nearly everything he did in foreign affairs—from the Balkan wars to the Good Friday agreement—came under the cloud of Whitewater. Nixon’s list was shorter, but during Watergate his administration helped negotiate peace after the Yom Kippur War, brought about an end to the Arab oil embargo, and even conducted a triumphant foreign trip in the last months before his resignation.

Every political advantage brings a corresponding political weakness, and both Nixon and Clinton encountered the downside of turning abroad: Critics accused them of trying to use global affairs to distract from their political troubles. In October 1973, four days after the “Saturday Night Massacre,” and two weeks after Vice President Spiro Agnew’s resignation, Nixon ordered a global military alert, ostensibly in response to Soviet military movements, though critics viewed it as an attempt at distraction.